 The stock market is heating up, and some Wall Street bulls are turning even more positive. Among those adapting an increasingly bullish approach is Stifels Head of Institutional Equity Strategy, Barry Bannister, who believes the worst is behind us, freeing up the SP; 500 to continue its ascent. Previously calling for an aggressive rebound right before the markets March lows, he now projects that by the end of August, the SP; 500 will hit 3,250, reflecting an 8 rise from current levels.We now raise our SP; 500 price target to 3,250 by Aug-30, 2020 in 3 months, supported by economic survey data improvingbottoming consumer, services, industrial and our expectation that the SP; 500 price-to-earnings expands at prevailing low real bond yields to offset weak earnings per share, typical of late-stage recession periods, Bannister wrote in a note to clients.Bearing this in mind, some investors are on the hunt, looking to snap up compelling names before shares re-embark on an upward trajectory. For the more risk-tolerant, focus has locked in on penny stocks, or tickers trading for less than 5 per share. The appeal is clear; the bargain price tag means you can get more bang for your buck and even what feels like inconsequential share price appreciation can result in huge percentage gains.Whats the flip side? Minor share price depreciation can fuel major percentage losses. By nature of these massive movements, penny stocks are notoriously volatile. With an understanding of the risk at play, we used TipRanks database to pinpoint three penny stocks in the healthcare sector supported by the Streets analysts, with each receiving enough bullish calls to earn a Strong Buy consensus rating. Not to mention each offers up massive upside potential.Vascular Biogenics VBLTUsing its three platform technologies that enhance natural physiologic and genetic regulatory elements, Vascular Biogenics develops first-in-class treatments for cancer. With a key catalyst expected in the third quarter of this year, several analysts believe that at 1.15 apiece, now is the time to pull the trigger.The company has recently announced that data from the second interim assessment of efficacy for the Phase 3 OVAL study of its VB-111 candidate in platinum-resistant ovarian cancer patients will come in Q3, with the DSMC analysis set to evaluate 100 patients for survival after at least three months of follow-up.Writing for Oppenheimer, five-star analyst Kevin DeGeeter says that after having discussions with KOLs, he thinks the absolute mortality in both arms will be relatively high, landing within the range of 30-40 in the first three months of follow-up for advanced ovarian cancer patients.Expounding on the implications of the study, DeGeeter stated, In terms of interim assessment for OVAL, we view the update as an incremental step in evaluating the efficacy of VBL-111 with likely broad statistical intervals for futility. As such, we view risk of stopping the study for futility as low.On top of this, DeGeeter expects preclinical data from the MOSPD2 bi-specific antibody program to be presented at AACR on June 22-24. Abstracts for the meeting were released on May 15. This data release is especially significant as its an important step when it comes to expanding VBLTs pipeline, in the analysts opinion. He added, We view acceptance of preclinical MOSPD2 data for a late-breaking abstract as an important validation of the novel scientific approach.Looking more closely at MOSPD2, the protein, which is found on the surface of monocytes, neutrophils and lymphocytes, could stimulate myeloid cell migration. It should be noted that MOSPD2 is expressed on the surface of multiple tumor cell types and can promote tumor cell invasion. Based on our review of the literature, VBLT appears to have one of the most advanced cancer programs against this novel target, DeGeeter commented.To this end, DeGeeter reiterated his Outperform i.e. Buy rating on VBLT along with a 2.50 price target. Should this target be met, a twelve-month gain of 117 could be in store. To watch DeGeeters track record, click here Like DeGeeter, other analysts also take a bullish approach. VBLTs Strong Buy consensus rating breaks down into 5 Buys and no Holds or Sells. The 3.85 average price target is more aggressive than DeGeeters, with the upside potential coming in at 235. See VBLT stock analysis on TipRanksLineage Cell Therapeutics LCTXFocused on designing innovative cell therapies, Lineage Cell Therapeutics uses a cell-based therapy platform to develop differentiated cells to support or replace cells that are dysfunctional due to degenerative disease or traumatic injury. Currently going for 0.91 apiece, some members of the Street believe the share price reflects an attractive entry point.Weighing in for H.C. Wainwright, 5-star analyst Joseph Pantginis tells investors that he has high hopes following LCTXs recent data release. Earlier this month, the company published updated results from its Phase 12a study of OpRegen as a treatment of dry-AMD. Representing an exciting development, the results reported are the first of improved visual function recorded in the first patient enrolled in cohort 4 and treated with the Orbit SDS with thaw-and-inject formulation TAI, the trials exploratory goal.Expounding on this, Pantginis said, Importantly, the results confirmed and expanded prior observations of safety and improved vision upon treatment with OpRegen. Specifically, the data show meaningful improvements in the progression of geographic atrophy reduction, visual acuity, and reading speed. In addition, the results reinforce a growing body of evidence that OpRegen is well-tolerated and can provide sustained and clinically meaningful benefits with a single dose of RPE cells.Taking a more in-depth look at the study, cohort 4 included five patients treated with one of two formulations of OpRegen. The first three were given a formulation of OpRegen that required plating and preparation of cells one day prior to use and retinotomy, while the others were treated with Orbit SDS TAI. According to Pantginis, the results not only produced a significant and durable improvement in visual function, but also underscored the differences between the formulations. Not to mention the OpRegen with TAI via Orbit SDS formulation was found to be safe.If that wasnt enough, LCTX announced that it is applying for grant funding from the California Institute for Regenerative Medicine CIRM to support its development of a prophylactic vaccine against COVID-19. Even though IND enabling work including the creation of a specific expression construct and manufacturing process will be necessary, Pantginis argues that LCTXs non-dilutive funding strategy and solid scientific rationale at the basis of the technology de-risk the strategy.Based on all of the above, Pantginis reiterates a Buy rating on LCTX along with a 4 price target. This suggests upside potential of a colossal 340. To watch Pantginis track record, click here All in all, other analysts echo Pantginis sentiment. 3 Buys and no Holds or Sells add up to a Strong Buy consensus rating. Given the 3.67 average price target, the upside potential lands at 299. See LCTX stock analysis on TipRanksOnconova Therapeutics ONTXLast but not least we have Onconova Therapeutics, which develops small molecule drug candidates to treat cancer. With a price tag of only 0.39 per share and a major potential catalyst coming up in the second half of the year, its no wonder this stock is on Wall Streets radar.Part of the excitement surrounding ONTX is related to the data readout for the now fully enrolled pivotal Phase 3 INSPIRE study in high-risk myelodysplastic syndrome MDS patients. The study is evaluating IV rigosertib RAS-mimetic in patients who are under the age of 82 with high-risk MDS that have failed HMA therapy within nine months or nine cycles. Speaking to the data readouts significance, Maxim analyst Jason McCarthy stated, The Phase 3 INSPIRE result in 2H20 is a binary event for ONTX shares, in our view. Given the removal of any financing overhang with recent equity raises to strengthen the balance sheet, the data, if positive, will be transformative for the company, with strategic partners likely to take note as well as provide solid footing for the second intended Phase 3 study with rigosertib thereafter. Also important to consider, the company has two chances to receive approval. Key to remember is that the trial was designed with two shots on goal: either to reach p-value in the intent-to-treat ITT patients or the very-high-risk VHR subset. Patients with VHR have a life expectancy of six months, and 65 of the patients enrolled are VHR. Given what we saw in the ON-TIME subgroup, we believe the probability of success favors both scenarios, the 5-star analyst commented. Additionally, McCarthy cites other possible catalysts slated for 2020 including the start of enrollment for the Phase 12a KRAS-mutated lung cancer study IST of rigo and nivolumab, ON 123300s IND submission to the FDA and trial initiation as well as the initiation of the combination study for oral rigo and azacytidine in HMA-naïve higher-risk MDS patients.With everything ONTX has going for it, it should come as no surprise that McCarthy joined the bulls. In addition to upgrading his rating from Hold to Buy, he put a 1.25 price target on the stock. This target conveys his confidence in ONTXs ability to skyrocket 221 in the next year. To watch McCarthys track record, click hereTurning now to the rest of the Street, other analysts are on the same page. With 100 Street support, or 3 Buy ratings to be exact, the message is clear: ONTX is a Strong Buy. The 1.65 average price target brings the upside potential to 323. 